There are many human and veterinary diseases that stem from processes of uncontrolled or abnormal cellular proliferation. Most important among these diseases is cancer, the generic name given to a broad range of cellular malignancies characterized by unregulated growth and lack of differentiation. Psoriasis is another disease that is characterized by uncontrolled or abnormal cellular proliferation. Psoriasis is a common chronic skin disease characterized by the presence of dry scales and plaques. The disease results from hyperproliferation of the epidermis and incomplete differentiation of keratinocytes. Psoriasis often involves the scalp, elbows, knees, back, buttocks, nails, eyebrows, and genital regions, and may range in severity from mild to extremely debilitating, resulting in psoriatic arthritis, pustular psoriasis, and exfoliative psoriatic dermatitis. There is, at present, no general therapeutic cure that exists for psoriasis. Whilst milder cases are often treated with topical cortico-steroids, more severe cases may be treated with antiproliferative agents, such as the antimetabolite methotrexate, the DNA synthesis inhibitor hydroxyurea, and the microtubule disrupter colchicine.
Other diseases associated with an abnormally high level of cellular proliferation include restenosis, where vascular smooth muscle cells are involved; inflammatory disease states, where endothelial cells, inflammatory cells and glomerular cells are involved; myocardial infarction, where heart muscle cells are involved; glomerular nephritis, where kidney cells are involved; transplant rejection, where endothelial cells are involved; and infectious diseases such as HIV infection and malaria, where certain immune cells and/or other infected cells are involved.
Inhibition of cellular proliferation can be brought about by several mechanisms, including; alkylating agents; topoisomerase inhibitors; nucleotide analogues; antibiotics; hormone antagonists; and nucleic acid damaging agents; inter alia. One pharmacologically important mechanism of inhibiting cellular proliferation is by means of binding tubulin. Tubulin is an asymmetric dimer composed of alpha and beta subunits, that polymerizes to form structural components of the cytoskeleton called microtubules. Microtubules must be highly dynamic in order to carry out many of their functions. At certain stages of the cell cycle, or in particular cell types or organelles, stable microtubules are required, such as for transport within axons or for ciliary and flagellar movement. Micro-tubules assemble during the G2 phase of the cell cycle, and participate in the formation of the mitotic spindle which facilitates the segregation of sister chromatids during the process of cell division. The essential role of microtubules in cell division and the ability of drugs that interact with tubulin to interfere with the cell cycle have made tubulin a successful target for applications that include anti-cancer drugs, fungicides, and herbicides. Typical tubulin ligands such as colchicine, paclitaxel, the Vinca alkaloids such as vinblastine, the epothilones, the halicondrins, benomyl and mebendazole directly inhibit cell division by binding to tubulin which leads to the arrest of the cell cycle at the G2/M boundary of mitosis. This mechanism is the basis of the therapeutic value of compounds of this type, such as treating gout with colchicine, restenosis with paclitaxel, cancer with paclitaxel, vinblastine, epothilones and halichondrins, and fungal infections with benomyl and malaria and helminths with mebendazole.
Interfering with microtubule dynamics or stability can inhibit cell division in several ways. Both stablilizing microtubules or inhibiting their polymerization will prevent the cytoskeleton restructuring that is required at several points in the cell cycle and lead to an arrest of the cell's progression from one stage in the cell cycle to the next. Three main classes of tubulin-binding drugs, namely colchicine analogues, Vinca alkaloids, and the taxanes, have been identified, each of which possesses a specific binding site on the β-tubulin molecule. Paclitaxel (Taxol™) and related taxanes represent a class of drugs that stabilize microtubules, a process that ultimately leads to the “freezing” of the microtubule structures so that they cannot be restructured (Jordan M. A. and Wilson L., 1998). Subsequent arrest at mitosis induces the apoptotic mechanism to cause cell death. A number of colchicine analogues, as well as several other compounds that bind to the same site on β-tubulin as colchicine disrupt tubulin polymerization and disrupt microtubular formation. Vinblastine and several other vinca-related drugs bind to a site that is distinct from the colchicine site. Compounds that bind at the Vinca-site prevent microtubule formation and destabilize microtubules (Jordan et al, 1986; Rai and Wolff (1996). This invention is therefore directed to compounds that potentially modulate microtubule dynamics by binding to tubulin.
Accordingly, the present invention aims to provide compounds which are directly or indirectly toxic to actively dividing cells and are useful in the treatment of cancer, viral and bacterial infections, vascular restenosis, inflammatory diseases, autoimmune diseases, or psoriasis. The present invention is also directed to therapeutic compositions for treating said conditions. Further aspects of the invention are to provide methods for killing actively proliferating cells, such as cancerous, bacterial, or epithelial cells, and treating all types of cancers, infections, inflammatory, and generally proliferative conditions. A further aspect relates to provide methods for treating other medical conditions characterized by the presence of rapidly proliferating cells, such as psoriasis and other skin disorders.
In one embodiment, the method of the invention is used in the treatment of sarcomas, carcinomas and/or leukemias. Exemplary disorders for which the subject method can be used alone or as part of a treatment regimen include: fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilms' tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma, and retinoblastoma.
In certain embodiments, the method of the invention is to be used to treat disorders such as carcinomas forming from tissue of the breast, prostate, kidney, bladder or colon.
In other embodiments, the method of the invention is used to treat hyperplastic or neoplastic disorders arising in adipose tissue, such as adipose cell tumors, e.g., lipomas, fibrolipomas, lipoblastomas, lipomatosis, hibemomas, hemangiomas and/or liposarcomas.
In still other embodiments, infectious and parasitic agents (e.g. bacteria, trypanosomes, fungi, etc.) can also be controlled using the subject compositions and compounds.